Skip to content

Peptides / PEG-MGF

Review scheduledPegylated mechano growth factorNot FDA approved

PEG-MGF

PEG-MGF is a modified, longer-lasting version of mechano growth factor, a form of the growth hormone IGF-1 that muscle makes after exercise or injury. The PEG coating slows its breakdown in the body.

Main use
Muscle repair
Committee review
Review by Feb 2027
Strongest evidence
Animals
Legal to compound in the US
Not yet

Effects studied or claimed

What it is promoted for, and where each effect has actually been seen

  • Muscle repair and growthAnimals and lab studies

How it is thought to work

It is thought to activate muscle stem cells, which repair and build muscle fibres.

What the evidence shows

In animals and the lab

Muscle injury studies in animals and cell cultures.

In people

None.

Safety and unknowns

Unknown. Like other growth factors in the IGF-1 family, it raises a theoretical concern about promoting tumour growth. It is banned in sport.

FDA review

Scheduled for review by the FDA's compounding advisory committee before the end of February 2027.

Committee votes are advice to the FDA. A peptide can only be compounded legally once the FDA adds it to the 503A bulks list through formal rulemaking, which has no fixed deadline.

Sources

Analysis

A muscle growth factor that failed independent tests

Peptide Evidence IndexBiology 2/10In people 0.5/10Index 0.9, rank 15 of 15See the full index

Mechano growth factor is a version of IGF-1 that muscles make when they are stretched or damaged. It was identified at University College London in the mid-1990s by Geoffrey Goldspink's group (Yang and colleagues, 1996). PEG-MGF is a synthetic piece of it with a polyethylene glycol chain attached to make it last longer, and is sold to bodybuilders for muscle growth and recovery.

Early work was striking: Goldspink's group reported that MGF switched on muscle stem cells and that delivering its gene into mouse muscle increased muscle size within weeks. The independent follow-up was not. A 2014 study tested the synthetic MGF peptide on muscle cells and muscle stem cells from mice and humans and found no measurable effect on their growth or development (Fornaro and colleagues).

Our view. the natural splice form of IGF-1 is real, but the case for the synthetic peptide rests on early findings that independent researchers could not reproduce. There are no human trials of PEG-MGF, and it is banned in sport.

Studies and reports cited

  1. Yang S et al. Cloning and characterization of an IGF-1 isoform expressed in skeletal muscle subjected to stretch. J Muscle Res Cell Motil, 1996
  2. Fornaro M et al. Mechano-growth factor peptide, the COOH terminus of unprocessed insulin-like growth factor 1, has no apparent effect on myoblasts or primary muscle stem cells. Am J Physiol Endocrinol Metab, 2014

Summary of published research for general information. It is not medical advice and not a recommendation to use this substance.

← Melanotan IIAll peptidesSermorelin →

General information, not medical advice. Do not buy or inject unregulated peptides.